Substance use during pregnancy and while parenting can have profound effects on development. However, these consequences have rarely been directly measured in the same mothers and babies over time. The NIH seeks to create a national pregnancy cohort, ?HEALthy BCD,? that will follow pregnant women and their offspring exposed and unexposed to substances until age 10. Baltimore has high rates of opioid use and high prevalence of other risk factors for poor child health outcomes such as exposure to violence, toxicants, poor housing, and discrimination. These facts make Baltimore an important site for HEALthy BCD to help understand the independent and interacting roles of substance use and other environmental and social factors on child health. Johns Hopkins University (JHU) and our pediatric partner, the Kennedy Krieger Institute (KKI) have extensive and diverse expertise across every essential element required: opioids and other substances, longitudinal pregnancy cohorts, neurodevelopmental assessments, neuroimaging, maternal and child health services, ethical and legal issues, genomics and epigenomics, social and behavioral sciences, adverse childhood experiences, qualitative methods, and epidemiological and statistical tools. In response to the current 18-month planning phase request, we will expand a recently initiated pregnancy cohort at JHU called ORCHARD (ORigins of Child Health And Resilience in Development) to create a Baltimore HEALthy BCD site, named HEALthy ORCHARD. We will develop the critical partnerships and protocols necessary to create, build, and steward this cohort. We will also identify and plan solutions for ethical and legal challenges. Our activities will convene JHU/KKI investigators and community partners across nine work groups to (1) Develop protocols for recruitment and retention of pregnant mothers and children with enriched sampling of pregnant women who are using substances (2) Establish community, medical, and government partnerships necessary to implement recruitment, retention, data collection and community benefits (3s) Characterize the critical ethical and legal challenges raised during study design, in pilot studies, and by prospective participants, and propose solutions where possible, and additional research where necessary. (4) Develop protocols for longitudinal data collection across pregnancy and childhood to measure a) Pregnancy and early life maternal and child substance use exposures as well as other social, environmental, and genomic risk factors, b) Maternal and child health and neurodevelopmental outcomes from birth to age 10, c) Longitudinal neuroimaging, including pilot scans and analyses, where we will build upon the adolescent (ABCD) and baby connectome MRI protocols and add additional scans for more information regarding brain development, especially geared towards myelination changes in very early life, d) plan timing and types of biosamples to be collected, e) develop data science supports (5) Contribute to multi-site protocol development and nationally-relevant principles regarding ethical and legal issues.